1. Field of the Invention
The invention relates to a device for inscribing and/or reading a magneto-optical information carrier comprising a frame carrying a turntable which is rotatable about an axis of rotation, for supporting the information carrier, an optical unit which includes an objective for concentrating a radiation beam to form at least one radiation spot in a focusing plane, an actuator for moving the objective in a direction parallel to said axis of rotation, and a magnetic unit which, viewed according to said axis of rotation, is arranged opposite to and spaced from the optical unit, which magnetic unit comprises means for generating a magnetic field which extends into said focusing plane, the optical unit and the magnetic unit being arranged to be movable in a plane transverse to said axis of rotation.
2. Description of the Related Art
Such a device is known from published West German Offenlegungsschrift DE 37 23 134 (herewith incorporated by reference). Such prior art device for magneto-optically inscribing a magneto-optical disc comprises a housing having a cover which can be opened and closed to insert or remove a magneto-optical disc. During operation the magneto-optical disc loaded into the housing is held on a turntable by a disc-pressure member and is rotated by a drive motor. The drive motor is secured to a frame accommodated in the housing. The housing further accommodates a slide which is movable over rectilinear guide means in a radial direction relative to the axis of rotation of the turntable. The slide is constructed as a tilted U-shaped part having two mutually parallel radial limbs. One of the limbs carries an lens for concentrating a radiation beam to form a radiation spot and the other limb carries a permanent magnet for producing a magnetic bias field. The lens and the magnet are arranged opposite one another and are each situated at one side of the disc which is supported by the turntable.
An information carrier to be used for magneto-optical recording is provided with a thin film of a ferromagnetic or ferrimagnetic material having a direction of easy magnetisation perpendicular to the surface of the thin film. During recording it is necessary that the thin film be heated to a temperature above the Curie temperature, or in the case of ferrimagnetic materials to a temperature above the so-called compensation point. When the prior-art device is used the magneto-optical disc is inscribed by applying a magnetic bias field by means of the permanent magnet and by heating the thin film by means of a pulsed laser beam.